To determine whether the clinically disease-free interval accompanying adjuvant chemotherapy is a result of direct anti-cancer action, indirect endocrine organ changes, or a combination of 1 and 2. We intend to approach this problem in three separate ways. We will use a pre-menopausal patient population exhibiting stage II breast carcinoma, an intact and castrate in vivo model (rat), and two invitro tissue culture systems: anterior pituitary cells and mammary tumor cells.